Of the materials amalgamated and prepared in this way, the porcelain is made. This is done either with the wheel, like our eathen-ware, or in moulds All smooth dishes are made in the former way ; and the largest are finished on the wheel by two operations, one-half being applied at a • time. When the two halves have, in this way, been made to acquire the sage size and figure, they are united with porcelain earth, made liquid by adding water to it; and the juncture, which is polished by a kind of iron patula, is so perfect that it is not only entirely imperceptible, but is the strongest part of the vessel. It is in this way that handles, spouts, often embossed work, are added. Those vessels, on the contrary, that are embellished with figures in relievo, arc formed, not on the wheel, but in moulds, and are polished and finished with the chisel. Others that have impressions in creux, are engraven with a species of puncheon. Vessels with figures in relievo or in creux, belong, it is evident, in one re spect, at least, more to the profession of sculpture than to that of porcelain-making. This operation is, of consequence, as signed to a particular class of workmen; and as their labour is exclusively confined to this species of employment, it is performed with a degree of delicacy, rapidity, and elegance, which, considering the extreme brittleness of the article, is altogether astonishing. Nor is this the only department assigned to a separate class of workmen. On the contra ry, the division of labour is carried to a very great extent in the porcelain manufacture. Every separate operation, however minute, is done respectively by different persons; and a single cup runs with expedition from one to another, till, before it is finished, it has passed through the hands of no fewer than seventy individuals.
The Chinese, for many ages, used only white porcelain, which were first superseded by blue, and soon' afterwards every variety and shade of colour was introduced. The blue, it is supposed, they originally prepared from a species of lapis lazuli, which, previous to being used, was calcined, and reduced to a powder of the greatest fineness. But as Britain can supply them with the srnalt at a cheaper rate than they can prepare it,they obtain the article from this country. The fine deep blue, by which the most ancient china-ware was characterized, and which is so much valued by the curious, is now no longer to be seen. The art of making it, indeed, seems to be entirely lost ; though it is supposed to have been obtained from the of cobalt (with other minor pre parations;) a mineral which may be found in various parts of China and of the East. Nor is this the only art in the department of painting which, though once fully under stood, the Chinese have now altogether forgotten ; and, while it may be affirmed, with much truth, that while the manufacture of porcelain in China has not improved, in the smallest degree, these last live centuries, it has, in some respects. entirely deteriorated. In addition to the loss of the knowledge of producing the fine deep blue, as just mentioned, the art of making the magic porce lains has also entirely disappeared. These magic porcelains exhibit their colour and their devices only when filled with water, and were thus regarded as the most curious and ro mantic specimens of the art to which they belonged. Though the mode in which they were manufactured can not now be described with accuracy, the following has been conjectured as not very remote from the troth. The first requisite, which was quite indispensable, was, that the vessel be extremely thin, so that the figures to he formed might be sufficiently clear and perceptible. After the yes sel had been baked, (a process soon to be described,) the figures, which were mostly fish, as these corresponded best with the water, must be formed d n the inside ; and al „,ter the colour has had time to dry, a second extremely thin coat, of the same substance of which the vessel was constructed, must be inserted on the inside, and varnished. The fish, or whatever is the device, will now, it is evident, be buried between the two coats of the ware of which the vessel is made. eAll that now remains to be done, is to grind the outside of the vessel as close to the figures as possible, to varnish it again, to subject it a second time to the fumace; and though, alter the openation, the figures and embellishments will not be at all perceptible, yet so soon as the vessel is filled with water, they will all at once be rendered clear and distinct to a degree scarcely credi ble. This beautiful art it has hcen attempted of late years
to revive; but as the pains and delicacy required are so extremely great, and as the Chinese seem not now to be characterised by the same ingenuity or dexterity as in for mer ages, these attempts have hitherto been wonderfully unsuccessful.
It may here be mentioned with propriety, that though the painting of porcelain is distributed among a great va riety of workmen, each having his own department, this art has not attained to any eminence or perfection in the cast. With the exception of flowers and landscapes, which, though never remarkably elegant, are yet pretty correct and beautiful ; the other species of painting are total fail ures, deficient both in design and execution, and such as would bring disgrace on the merest tyro in the art in this quarter of the world. If the Chinese, however, do not ex cel in painting, the colours which they use are prepared with a degree of niceness and skill of which there is yet no instance in Europe, and are indeed so lively and brilliant as to challenge all rivalry.
The different colours by which the Chinese porcelain is distinguished, are made from the oxyds or different me tals, with other slight ingredients, prepared and amalg; mated in a way which, as just remarked, we cannot success fully imitate or understand. On this curious subject, al most the only information we possess is derived from Clou et and 13rogniart. (Vide Philosolzkical Magazine, vol. vii. p. I, and Nicholson's Journal, vol. iii. p. 1.) The follow ing brief sketch will, we fear, afford the reader but a faint idea of the important art in question. Carmine red is obtained from the purple precipitate of the solution of gold, by muriate of tin. 'This beautiful colour, how ever, is now comparatively lit tle used, as it is apt to change from the great heat necessary to bake the vessel after it is applied. Violet results from the application of the same substances with a larger quantity of oxyd of lead. Rose red is produced by the oxyd of iron, highly oxydized by the action of nitric acid. For this purpose, the purest iron is dissolved in strong nitric acid ; and the solution thus obtained must be allowed to stand till it is perfectly clear. Then add a solution of the carbonate of potash, till the whole of the oxyd of iron is precipitated. This precipitate must now be washed carefully with hot water, and the last washing drawn off by heat, raised al most to redness—which wilt expel the carbonic acid. The oxyd, after this operation, will have assumed a fine red colour, and be fit for application. The white oxyd of an timony, with oxyd of lead and silex, is employed-to give a yellow colour. Blue, as formerly hinted, is produced from oxyd of cobalt ; green from oxyd of copper; brown from various proportions of manganese, copper, and iron mixed. The colours thus obtained are applied to the sur face of porcelain by means of fluxes or enamels, more fu sible than the matter of the porcelain. ” The flux gene rally employed to fix the colouring matter," says a celebra ted chemist, " is either a mixture of v,itrific oxyd of lead and silex or borax, or sometimes a mixture of all these. By promoting the fusion of the metallic oxyd, it causes it to adhere at a lower heat than that by which it might be decomposed, and the colour changed; it also serves as a medium of union with the matter of the porcelain, and renders the surface more smooth. The method of ap plying it is, either to mix the metallic oxyd, or mixture of oxyds, which is to give the colour, with the materials of the flux, the whole being reduced to an impalpable pow der, which is made into a thick liquid with gum water, or with a volatile oil, and applied by a pencil to the surface of the unglazed porcelain ; or the colouring matter and the matter of the flux are fused together, and the enamel thus formed being reduced to a fine powder, is applied in a si milar manner. The first mode is generally employed with those colours which are liable to he altered by heat." The common kinds of porcelain, it may be remarked, are by means of copper-plate prints, which, however, are more used in common earthenware than in porcelain.